Need advice regarding engine noise I'm chasing -
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post #1 of 6 Old 03-16-2014, 01:52 PM Thread Starter
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1997 ZJ 
Join Date: Mar 2014
Location: Belleville
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Need advice regarding engine noise I'm chasing

Hello all,
My first post here. Have read everything I can but would like some advice on my situation. I have a 97GC 4.0 w/ 170K. Bought with ticking on cold starts when under load. Would go away after couple minutes. Popped valve cover. All seems ok. No loose rockers, pushrods spin freely and are straight. Not able to compress lifters. Turned engine to diff points and rechecked everything. Also ran it to check for oil flow to each area and it was consistantly good.
Tried seafoam in oil, restore, thicker oil, etc. No change. Now it seems to be getting louder and not going away completely as previous. Doesn't seem to be exh manifold or gasket leak as there is a distinct metal to metal contact noise and slight vibration associated with it. Popped valve cover for a 2nd time and all seemed fine as it did 1st time. Not sure if I am putting enough pressure on lifters to truly test them. No build up in there either. Have also pulled 1 sparkplug wire at a time ( with friend revving and in gear)but each time was the same, misfire with engine rocking but noise still there. Oil pressure is good staying above 35 at idle and up around 50 driving and have verified this w/ a gauge in place of the sender. Yesterday I dropped the oil pan. No sludge build up there either, no signs of excessive heat on any of the bearings or pistons. cannot find any vertical movement in any rod bearings. No scoring to cylinders. No chunks of skirt in pan or cracks in pistons. The timing chain does seem to be too lose but the noise seems to be from the rear.
Anything else I should be looking for with the pan off?
Is it possible I do have a bad lifter that is not noticeable from on top of the head?
Anyone who takes the time to read this and share any advice or your experiences, I appreciate and thank you in advance.


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post #2 of 6 Old 03-16-2014, 02:10 PM
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check converter bolts, may not even be in the motor, could be a wrist pin also, and you're positive it's not a exhaust issue

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post #3 of 6 Old 03-16-2014, 02:28 PM
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Had a friend go through the same sort of thing. His cold start click sounded like it was coming form the bottom rear of the engine. They checked everything on top and found it tight. They did replace a valve rocker that seemed a little loose. None of which helped. They then thought it was something like the fly wheel bolts coming loose or the starter gear not pulling away, the crank hitting the pan and so on...

In the end it turned out to be a bad lifter. Even though everything looked fine at first. They ended up pulling each one out separately until they found the one that was stuck.
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post #4 of 6 Old 03-17-2014, 07:10 AM
2004 TJ Wrangler 
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This is fairly common with an older 4.0. In colder climate a thinner oil is needed at startup. A lifter may be sticking while cold. This is NOT the death of the engine. I dont know how far north you are but in Chicagoland we have had the coldest winter in history so you have too. A 5W or 0W oil will help at startup in this brutal weather. This will flow much better than a heavier oil.I understand the thought process of a thicker oil but its flawed. I used to believe this also. The thicker oil doesnt flow well in the extreme cold making the ticking even worse. Here is some reading that may help you.
Sadly your engine is getting old but not worn out, just not new. This is a common ailment of this engine. Mine are at 176K and 216K. They both tick sometimes at startup and sometimes not. They have been doing this for over 50K each. So the chance that this is a major catastrophy is very slim. More a pain in the ***. Many have replaced the cam and lifters only to have the noises run quickly. The thin oil makes mine quieter but not always.


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post #5 of 6 Old 03-18-2014, 10:37 AM Thread Starter
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1997 ZJ 
Join Date: Mar 2014
Location: Belleville
Posts: 3
more info

Thank u guys for the responses. The reason I tried thicker oil was to help a possible loose bottom end bearing, but didn't help. So lastnight with pan off, I turned the crank, inspected everything, replaced the rear main seal, cam lobes look great, minimal crank & cam end play, nothing seems loose. So I buttoned it up. Today I'm gonna pull the valve cover again and have someone rev it in gear to produce noise and put pressure on each spring, rocker, etc to c id any change in noise. The nose seems really excessive for normal lifter tick.
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post #6 of 6 Old 03-19-2014, 11:29 AM Thread Starter
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1997 ZJ 
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Update: the noise I was hearing at the back cyl must have just been piston slap, cuz I checked again with some one revving this time and the louder ticking/clack noise is definitely from the front. Noticed that the front rocker didn't fill with oil nearly as fast as the rest did, and continuous flow is certainly slower. I wonder if is possible to push anything stuck in the lifter passage, back thru to clear it. I know the push rods are all clear. Just checked them, the rockers, bridges and tips of the lifters for damage or abnormal wear and all looked consistently good. Oil pressure checked good in place of sender. Any ideas?
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